alembic 命令

常用示例

说明

Alembic is a database migration tool for SQLAlchemy, Python's popular ORM. It manages incremental, reversible changes to database schemas through version-controlled migration scripts. Migrations are Python files stored in a versions directory. Each migration has an upgrade() function to apply changes and a downgrade() function to reverse them. Alembic tracks the current database state in a special table, allowing it to determine which migrations need to run. The --autogenerate feature compares SQLAlchemy model definitions against the current database schema to automatically generate migration scripts. While convenient, generated migrations should be reviewed as autogenerate cannot detect all types of changes. Configuration is stored in alembic.ini, which specifies the database URL, migration script location, and other settings. The env.py script in the alembic directory handles migration environment setup and can be customized for complex scenarios.

参数

init _directory_

Initialize a new Alembic environment in the specified directory.

revision _-m message_ _--autogenerate_

Create a new migration revision file.

upgrade _revision_

Upgrade database to a target revision (use 'head' for latest).

downgrade _revision_

Downgrade database to a target revision (use '-1' for one step back).

current

Show the current revision of the database.

history

List revision history.

heads

Show all current head revisions.

branches

Show all branch points.

stamp _revision_

Set the revision table to a specific version without running migrations.

show _revision_

Display details of a specific revision.

merge _revisions_ _-m message_

Merge multiple branch heads into one.

-c, --config _file_

Path to alembic.ini configuration file.

-n, --name _name_

Name of config section to use.

-x _key=value_

Pass additional arguments to env.py.

--autogenerate

Auto-generate migration by comparing models to database.

--sql

Output SQL instead of applying migrations.